Abstract-Exploration of high risk terrain areas such as cliff faces and site construction operations by autonomous robotic systems on Mars requires a control architecture that is able to autonomously adapt to uncertainties in knowledge of the environment. We report on the development of a software/hardware framework for cooperating multiple robots performing such tightly coordinated tasks. This work builds on our earlier research into autonomous planetary rovers and robot arms. Here, we seek to closely coordinate the mobility and manipulation of multiple robots to perform examples of a cliff traverse for science data acquisition, and site construction operations including grasping, hoisting, and transport of extended objects such as large array sensors over natural, unpredictable terrain. In support of this work we have developed an enabling distributed control architecture called control architecture for multirobot planetary outposts (CAMPOUT) wherein integrated multirobot mobility and control mechanisms are derived as group compositions and coordination of more basic behaviors under a task-level multiagent planner. CAMPOUT includes the necessary group behaviors and communication mechanisms for coordinated/cooperative control of heterogeneous robotic platforms. In this paper, we describe CAMPOUT, and its application to ongoing physical experiments with multirobot systems at the Jet Propulsion Laboratory in Pasadena, CA, for exploration of cliff faces and deployment of extended payloads.

Critical to the success of composite repair of metallic aircraft structures is the integrity of the bond between the base aluminum panel and the reinforcing high-strength composite patch. Monitoring of the repair is equally important to insure the composite patch integrity throughout the service life of the structure. Described in this paper are the test methods and results of a vibration signature-based technique used to qualitatively identify a de-bond on several different composite repair coupons. The high-frequency domain vibration signature from the test coupon is obtained using a single patch of piezoelectric material (Lead Zirconate Titanate or PZT), functioning both as an actuator and sensor. The vibration signature is obtained as a variation in electrical impedance of the piezoelectric patch, while driven by a fixed alternating electric field over a frequency range. The current drawn by the actuator is modulated due to the structure's inherent dynamic characteristics. The modulated electrical impedance which is analogous to the frequency response function, but much more easily obtainable, is an indication of vital dynamic structural behavior and is used to identify damage. Damage is simulated by either growing an existing pre-crack under the composite patch through cyclic loading or by creating a de-bond close to the edge of the repair patch. High frequency excitation, which is greatly facilitated by the electrically driven low-power compact PZT patch, is critical to the success of this technique because it assures a clearly visible change in the impedancelvibration signature even for very minor damage/changes. The technique has met with great success in the first stage of this development effort. Even a very minor de-bond or crack growth, has been clearly detected.t~e s e a r c h Scientist, Member AIAA, ASME. f~r a d u a t e

Europa is a premier target for advancing both planetary science and astrobiology, as well as for opening a new window into the burgeoning field of comparative oceanography. The potentially habitable subsurface ocean of Europa may harbor life, and the globally young and comparatively thin ice shell of Europa may contain biosignatures that are readily accessible to a surface lander. Europa’s icy shell also offers the opportunity to study tectonics and geologic cycles across a range of mechanisms and compositions. Here we detail the goals and mission architecture of the Europa Lander mission concept, as developed from 2015 through 2020. The science was developed by the 2016 Europa Lander Science Definition Team (SDT), and the mission architecture was developed by the preproject engineering team, in close collaboration with the SDT. In 2017 and 2018, the mission concept passed its mission concept review and delta-mission concept review, respectively. Since that time, the preproject has been advancing the technologies, and developing the hardware and software, needed to retire risks associated with technology, science, cost, and schedule.

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